JPH11298091A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress heat generation and to reduce introduction of defects, such as transfer in a nitride semiconductor layer. SOLUTION: An n-type Be1-x Mgx Se layer 9, and n-type Iny Ga1-y N layer 10, an n-type Ga0.9 Al0.1 N cladding layer 11, an MQW active layer 12, a p-type Ga0.9 Al0.1 N cladding layer 13 and a p-type GaN contact layer 14 are stacked in sequence on an n-type GaAs substrate 8. As for the n-type Be1-x Mgx Se layer 9, the value of x continuously changes. On the side in contact with the n-type GaAs substrate 8, x=1. On the side in contact with the n-type Iny Ga1-y N layer 10, the value of y changes continuously. On the side in contact with the n-type Be1-x Mgx Se layer 9, y=1. On the side in contact with the n-type Ga0.9 Al0/1 N cladding layer 11, y=0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device.

[0002]

2. Description of the Related Art Nitride semiconductors such as GaN, InN, and AlN are suitable as materials for use in blue semiconductor laser devices and semiconductor devices such as transistors that operate at high temperature and high speed. Here, a blue semiconductor laser will be described as an example of the nitride semiconductor device, and the related art will be described.

The structure of a conventional blue semiconductor laser has a sapphire substrate 1 and a laser structure 2 laminated thereon, as shown in FIG. The laser structure 2 includes an n-type GaN buffer layer 3, an n-type Ga _0.9 Al _0.1 N clad layer 4, a multiple quantum well (hereinafter referred to as MQW) active layer 5, a p-type Ga _0.9
An Al _0.1 N cladding layer 6 and a p-type GaN contact layer 7 are sequentially laminated. MQW active layer 5
Although not shown, In _0.02 Ga _0.98 N layer and In _0.15
It is manufactured by alternately stacking Ga _0.85 N layers. Although not shown, a part of the laser structure 2 is removed by etching to expose the n-type GaN buffer layer 3, and an n-type electrode is stacked on the surface. Further, a p-type electrode is stacked on the p-type GaN contact layer 7. The blue semiconductor laser is mounted on a suitable heat radiator (not shown) so that the sapphire substrate 1 is in contact therewith.

[0004]

In the above-mentioned conventional blue semiconductor laser, the sapphire substrate 1 is an insulating substrate and its thermal resistance is larger than that of the laser structure 2, so that the heat generated in the MQW active layer 5 is reduced. It was not possible to effectively escape to the heat radiator, so that laser operation at high temperatures was extremely difficult. In addition, since the difference in lattice constant between the sapphire substrate 1 and the laser structure 2 is large, dislocations enter the MQW active layer 5, which shortens the life of the blue semiconductor laser. Further, since the p-type electrode and the n-type electrode are in the same direction as viewed from the sapphire substrate 1 side, compared with a semiconductor laser having an electrode on the back surface of the substrate, such as a red semiconductor laser laminated on a GaAs substrate, for example. The area of the element has almost doubled, so that the number of semiconductor lasers obtained from one substrate has decreased, and the price per semiconductor laser has been high.

An object of the present invention is to provide an inexpensive nitride semiconductor device which has good heat dissipation, less introduction of defects such as dislocations, and is inexpensive.

[0006]

In order to solve the above problems, a semiconductor device according to the present invention comprises a conductive substrate, a buffer layer laminated on the conductive substrate, and a buffer layer laminated on the buffer layer. A buffer layer, the buffer layer includes a layer made of a group II-VI compound semiconductor having the same conductivity as the conductive substrate, and the semiconductor layer has a layer made of a group III-V nitride semiconductor. Including.

With this configuration, heat generated in the semiconductor layer can be released through the conductive substrate, and an electrode can be provided on the back surface of the conductive substrate.

Further, a semiconductor device of the present invention has a conductive substrate, a buffer layer laminated on the conductive substrate, and a semiconductor layer laminated on the buffer layer. Is I having the same conductivity as the conductive substrate.
The semiconductor device includes a layer made of a group I-VI compound semiconductor, and the semiconductor layer includes a layer made of a group III-V nitride semiconductor, wherein the II-VI group compound semiconductor is Be _x Zn _1-x
Se, Be _x Mg _1-x Se, Zn _x Mg _1-x S and ZnS
_x Se _1-x (0 ≦ x ≦ 1), in which the value of x changes continuously.

With this configuration, since the value of x continuously changes, lattice matching can be performed with both the conductive substrate and the semiconductor layer.

Further, a semiconductor device of the present invention has a conductive substrate, a buffer layer laminated on the conductive substrate, and a semiconductor layer laminated on the buffer layer. Has the same conductivity as the conductive substrate II
-A layer made of a group VI-compound semiconductor, wherein the semiconductor layer includes a layer made of a group III-V nitride semiconductor;
It is composed of at least two kinds of compounds among eSe, MgSe, ZnSe, MgS and ZnS.

With this configuration, defects such as dislocations generated from the interface between the conductive substrate and the buffer layer can be absorbed by the buffer layer.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a blue semiconductor laser according to a first embodiment of the present invention has an n-type Be _1-x Mg _x Se layer 9 having a thickness of 1 μm on an n-type GaAs substrate 8. N _- type In _y Ga _1-y N layer 10 with a thickness of ₁ μm, n-type In _y Ga _1-y N layer with a thickness of 2 μm
Ga _0.9 Al _0.1 N clad layer 11, MQW active layer 1
2. p-type Ga _0.9 Al _0.1 N cladding layer 1 having a thickness of 2 μm
3. It has a structure in which p-type GaN contact layers 14 each having a thickness of 1 μm are sequentially laminated. MQW active layer 12
Is a not shown layer thickness of 30Å In _0.15 Ga _{0. 85} N
The layers and the In _0.02 Ga _0.98 layers having a thickness of 70 ° are alternately laminated to form a 20-layer structure. Also, n-type Be _1-x M
As for the g _x Se layer 9, the value of x changes continuously, and x = 1 on the side in contact with the n-type GaAs substrate 8,
x = 0 on the side in contact with the n-type In _y Ga _{1 -y} N layer 10. Similarly, for the n-type In _y Ga _1-y N layer 10, the value of y changes continuously, and the n-type Be _1-x Mg _x Se layer 9
On the side in contact with the n-type Ga _0.9 Al _0.1 N cladding layer 11, y = 1.

The n-type Be _1-x Mg _x Se layer 9 is laminated by using a molecular beam epitaxial growth method (hereinafter, referred to as MBE method), from the n-type In _y Ga _1-y N layer 10 to the p-type GaN contact layer 14. Are stacked using a metalorganic vapor phase epitaxial growth method (hereinafter referred to as MOVPE method).

Further, the blue semiconductor laser thus constructed is mounted on a suitable heat radiator (not shown) such as a copper block so that the n-type GaAs substrate 8 is located below.

According to such a configuration, since the n-type GaAs substrate 8 having conductivity is used, an electrode can be provided on the back surface of the n-type GaAs substrate 8, and the semiconductor laser obtained from one substrate can be obtained. Can be increased as compared with the conventional case, and the price per semiconductor laser can be made lower than before. Further, since the thermal resistance of the n-type GaAs substrate 8 is equal to or less than １ ／ of the thermal resistance of the sapphire substrate, the heat generated in the MQW active layer 12 can be released to the radiator directly through the substrate. Further, by continuously changing the value of the composition x of the n-type Be _1-x Mg _x Se layer 9 from 0 to 1, both the n-type GaAs substrate 8 and the n-type In _y Ga _1-y N layer 10 Lattice matching with the n-type In _y Ga _1-y N layer 10
Can be lattice-matched with both the n-type Be _1-x Mg _x Se layer 9 and the n-type Ga _0.9 Al _0.1 N cladding layer 11 by continuously changing the value of the composition y from 0 to 1. In addition, introduction of defects such as dislocations into the MQW active layer 12 can be reduced.

In the first embodiment, n _- type Be _1-x Zn _x Se is used instead of n _- type Be _1-x Mg _x Se layer 9.
Layers, n-type Mg _1-x Zn _x Se layers, ZnS _x Se _1-x layers, etc.
I-VI compound semiconductor mixed crystals may be used.

The blue semiconductor laser according to the second embodiment of the present invention has an n-type Si substrate 1 as shown in FIG.
5, an n-type II-VI group thin film buffer layer 16 having a layer thickness of 1
μm n-type In _y Ga _1-y N layer 10, n-type Ga _0.9 Al _0.1 N cladding layer 11 having a thickness of 2 μm, MQW active layer 12,
It has a structure in which a p-type Ga _0.9 Al _0.1 N cladding layer 13 having a thickness of 2 μm and a p-type GaN contact layer 14 having a thickness of 1 μm are sequentially laminated. As shown in FIG. 2 (b), the n-type II-VI group thin film buffer layer 16 has a thickness of 100 ° and has an n-type conductive ZnSe layer 17, a ZnS layer 18, a BeSe layer 19 and a ZnS layer. Layer 2
0 are sequentially laminated, and the ZnSe layer 17, the ZnS layer 18, and the BeSe layer 19 are further repeated 49 times.
Are laminated. Further, with respect to the n-type In _y Ga _1-y N layer 10, the value of y continuously changes, and the n-type
On the side in contact with the group VI thin film buffer layer 16, y = 1, and on the side in contact with the n-type Ga _0.9 Al _0.1 N cladding layer 11, y = 0.

The n-type II-VI group thin film buffer layer 16 is made of M
They are stacked using the BE method. Also, n-type In _y Ga
M from the _1-y N layer 10 to the p-type GaN contact layer 14
The layers are laminated using the OVPE method.

Further, the blue semiconductor laser thus constructed is mounted on a suitable heat radiator (not shown) such as a copper block so that the n-type Si substrate 15 is located below.

According to such a configuration, since the n-type Si substrate 15 having conductivity is used, the n-type Si substrate 15
Electrodes can be provided on the back surface of the semiconductor laser, and the number of semiconductor lasers obtained from one substrate can be increased as compared with the conventional case, and the price per semiconductor laser can be reduced as compared with the conventional case. Further, since the thermal resistance of the n-type Si substrate 15 is 1/5 or less of the thermal resistance of the sapphire substrate, the heat generated in the MQW active layer 12 can be released to the radiator directly through the substrate. Further, the n-type II-VI group thin film buffer layer 16 is
By repeating the multiple structure 21 in which the ZnSe layer 17, the ZnS layer 18, the BeSe layer 19, and the ZnS layer 20 are sequentially stacked, defects such as dislocation generated from the interface of the n-type Si substrate 15 can be reduced to an n-type II-VI thin film. Since the absorption can be performed by the buffer layer 16, the introduction of defects such as dislocations into the MQW active layer 12 can be reduced.

The blue semiconductor laser according to the first embodiment of the present invention, the blue semiconductor laser according to the second embodiment of the present invention and
FIG. 3 shows the results of a life test when the device was operated under the condition of a laser output of 5 mW. In FIG. 3, curves A, B and C represent a blue semiconductor laser according to the first embodiment of the present invention (hereinafter referred to as laser A) and a blue semiconductor laser according to the second embodiment of the present invention (hereinafter referred to as laser B). ) And a conventional blue semiconductor laser (hereinafter referred to as “laser C”). FIG.
It is known that, as the change rate of the operating current with respect to the operating time becomes closer to 1, the degree of laser deterioration is smaller and the life is longer. From FIG. 3, it was found that the laser A and the laser B had a smaller change rate of the operating current with respect to the operating time than the laser C and had a longer life. It is considered that this is because the laser A and the laser B have better heat dissipation than the laser C, and the introduction of defects such as dislocations into the MQW active layer is small. In addition, the operation time is 1
After elapse of 0000 hours, it was found that laser B had a smaller rate of change in operating current with respect to operating time than laser A, and had a longer life. This is presumably because laser B introduces less defects such as dislocations into the MQW active layer than laser A.

In the second embodiment, the n-type II-VI group thin film buffer layer 16 has a superlattice structure composed of a BeSe layer and a ZnSe layer, BeSe and Mg.
A plurality of thin films made of a II-VI compound semiconductor may be used, such as a super lattice structure made of Se, a super lattice structure made of a ZnS layer and a MgS layer, and a super lattice structure made of a ZnS layer and a ZnSe layer.

In the above-described embodiment, a conductive substrate such as an n-type GaP substrate or an n-type SiC substrate may be used instead of the n-type GaAs substrate 8 or the n-type Si substrate 15.

In the above embodiment, the case of a blue semiconductor laser has been described. However, the present invention may be any device made of a compound semiconductor, for example, a light emitting diode, a field effect transistor, or the like. The effect of is obtained.

[0026]

As described above, according to the semiconductor device of the present invention, heat generated in the semiconductor layer can be released through the conductive substrate and defects such as dislocations are introduced into the group III-V nitride semiconductor layer. Can be reduced,
The heat dissipation of the semiconductor device can be improved as compared with the related art, and the semiconductor device can be obtained at a lower cost than the related art. Further, since the buffer layer can be lattice-matched with both the conductive substrate and the semiconductor layer, introduction of defects such as dislocations into the semiconductor layer can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a blue semiconductor laser according to a first embodiment of the present invention.

FIG. 2A is a sectional view of a blue semiconductor laser according to a second embodiment of the present invention; FIG.

FIG. 3 is a diagram comparing the results of life tests of the blue semiconductor laser according to the first embodiment of the present invention, the blue semiconductor laser according to the second embodiment, and a conventional blue semiconductor laser.

FIG. 4 is a cross-sectional view of a conventional blue semiconductor laser.

[Explanation of symbols]

Reference Signs List 8 n-type GaAs substrate 9 n-type Be _1-x Mg _x Se layer 10 n-type In _y Ga _1-y N layer 11 n-type Ga _0.9 Al _0.1 N cladding layer 12 MQW active layer 13 p-type Ga _0.9 Al _0.1 N cladding Layer 14 p-type GaN contact layer 15 Si substrate 16 n-type II-VI group thin film buffer layer 17 ZnSe layer 18 ZnS layer 19 BeSe layer 20 ZnS layer 21 Multiple structure

Claims (7)

[Claims] 1. A semiconductor device comprising: a conductive substrate; a buffer layer laminated on the conductive substrate; and a semiconductor layer laminated on the buffer layer, wherein the buffer layer is the same as the conductive substrate. A semiconductor device comprising a layer made of a group II-VI compound semiconductor having the above-mentioned conductivity, wherein the semiconductor layer includes a layer made of a group III-V nitride semiconductor. 2. The semiconductor device according to claim 1, wherein the group II element constituting said group II-VI compound semiconductor is made of at least two elements of Be, Zn and Mg. 3. The method according to claim 1, wherein the II-VI compound semiconductor is ZnS.
_2. The semiconductor device according to claim 1, wherein _x Se _1-x (0 ≦ x ≦ 1). 4. The semiconductor device according to claim 1, wherein the number of layers of the II-VI compound semiconductor is two or more. 5. The semiconductor device according to claim 1, wherein the II-VI compound semiconductor is Be _x
Zn _1-x Se, Be _x Mg _1-x Se and Zn _x Mg _1-x S
3. The semiconductor device according to claim 2, wherein (0 ≦ x ≦ 1). 6. The semiconductor device according to claim 1, wherein said II-VI group compound semiconductor is Be _x
One of Zn _1-x Se, Be _x Mg _1-x Se, Zn _x Mg _1-x S and ZnS _x Se _1-x (0 ≦ x ≦ 1), and the value of x is continuously The semiconductor device according to claim 3, wherein the semiconductor device changes. 7. The layer made of a II-VI group compound semiconductor may be composed of BeSe, MgSe, ZnSe, MgS, and Z.
5. The semiconductor device according to claim 4, comprising at least two kinds of compounds among nS.